Crosslinked coating compositions that are based on an amine component typically are produced from two component systems that, when the two components are mixed together rapidly, cure at ambient conditions. The pot life of such coating compositions produced from amine functional components can be extended by converting the amine component to a related salt complex. For example, when carbon dioxide (CO2) is reacted with amine, the amine forms a carbamate salt that is solid at room temperature. Upon heating, the CO2 complexed with the carbamate salt is released and a liquid amine is then regenerated to function as a curing agent for the coating composition. Upon reaction of the amine with an isocyanate, polyurea may be formed. Other functional groups reactive with an amine may be included to produce other coating compositions.
In this process, an amine that is liquid at ambient conditions can be added to a solvent and gaseous CO2 is bubbled through the solution in order to react the CO2 with primary amines and/or secondary amines and form a carbamate salt. It is believed that the carbamate formulation occurs by forming a carbamic acid moiety in the presence of an amine (primary or secondary) whereby the carbamic acid protonates and forms a salt. Such salt complexes have been used to produce powder coating applications requiring an amine.